Engine control system



Feb. 20, 1951 w. J, RADY ET AL 2,542,703

ENGINE CONTROL SYSTEM Filed April 29, 1949 V 2 Sheets-Sheet 1 Car/M55360 Ale FUEL TANK if M/(LLJAM J. PADY 2 LYN/4 A. 2/65 774 5/ a /47 ToeNz-Ys Feb. 20, 1951 Filed April 29, 1949 2 Sheets-Sheet 2 W. J. RADY ET AL ENGINE CONTROL SYSTEM LYMAA/ THE/x; ATTORNEYS Patented Feb. 20, 1951 UNITED STATES PATENT OFFICE 2,542,703 ENGINE CiiN'rRoI. sYs'rEivi William J. Rady and Lyman A. Rice, Anderson, 1nd,, assig'nors to General Motors Corporation, Detroit, Mich a corporation of Delaware Application April 29, 1949, Serial Nb. 90,294 6Claims. (c1.192 3) This application is a continuation-impart of copending application, Serial No. 10,754, filed February 25, 1948, and now abandoned.

This invention relates to a system of control for an automotive vehicle, for example, a passenger bus propelled by a Diesel engine; and its object is to protect the engine in case of emergency, such as overheating or lack of magma ing oil, by causing the engine and the vehicle to stop regardless of failure of the operator to stop the engine by manual control. The present in vention provides an electrical system of control for a vehicle comprising an engine fuel control valve spring biased to open position, a solenoid for closing the valve, a normally open emergency switch whichcloses in case of abnormal engine operating conditions, a two-way manually operated switch having "on and foff positions, a current source, means rendered ef; fective by positioning the manually operated switch in on position and by closure of the emergency switch for causing the solenoid to be energized sufliciently by the current source to close the fuel valve and means rendered effective in response to movement of the manually operated switch to off position for effecting disconnection of the solenoid from the current source. I V

Further'ob'jects and. advantagesof the present invention will be apparent from the following description, reference being had to the acconrpanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a wiring diagram of an-embodiment of the present invention and includes diagram matic illustrations of a Diesel enginefuel system, an air brake system and switches which are controlled by conditions of engine operation.

Figs. 2 to 6 are wiring diagrams of portions of Fig. 1 and are referred to in the explanation of the mode of operation.

The engine is controlled manually in the con ventional manner by a fuel valve (not shown) which, when opened, permits the engine to operate after being started and which, when closed, causes the engine to stop. Referring to Fig. 1, the engine is stopped automatically by a solenoid In which, when energized, closes the engine fuel valve. The solenoid I is used only to close the fuel valve and after the valve is closed, the sole noid is automatically deener'gized. The solenoid is energized to close the fuel valve by an automatic control which responds to excessive temperature of the engine and to insufiicient lubrieating oil.

Solenoid H1 is connected with the frame ll of a relay l5 having a core l6 surrounded by windings l2 and I3 and having an armature |1 connected by a spring hinge H! with the frame l4. Rivets l9 secure to the armature a; blade '20 carrying a contact 2| engageable with a; contact 22. Armature carries a stud 23" which passes through a hole in the blade 20' and through a slot in the bimetal blade 24 secured to a support 25. The function of the blade 24 is to bend upwardly upon being heated in order to effect separation of contact 2| from contact 22 under certain conditions although the relay may be energized. 26 is a resistance element for heating the bimetal blade 24. Coil II is connected with ground and with a wire 21. Coil I2 is connected with contact 22 and with a wire 28 with which a curfent source 30, such as a storage battery, is connected. One end of coil I3 is connected with the core l6 and through the frame M with the solenoid Ill. The other end of coil I3 is connected with externali'e- 'sistances 29 which are grounded. Wire 28 is connected with a manually operated toggle switch 3| which, in off position, engages a com tact 32 and. which, in on position 3|, engages a contact 33. Switch 3| is so connected with a manually operated member (not shown) for con=-. trolling a part of the bus so that movement of said member to'render operative the door operat ing mechanism, for e'xar'nple, causes the switch 3| to move to on position. Contact 32 is con: nected through wire 34 with relay contact 22 and with contact 36 of a thermal switch having a bimetal flip disc 31 connected by wire 39 with switch contact 33. Disc 31 carries a non cone ducting block 40 supporting a spring blade 4| carrying a contact 42 normally engageable with a grounded contact 43. Blade 4| is connected with heater resistance 26 of the relay I5. Contact 36 is normally out of engagement Witha contact 44 located on the underside of the flip disc 31 which carries, on its upper side, a com tact 45 engageable with a contact 46 connected with wire 21 and with a heater resistance 41 connected with a buzzer or a bell magnet 48 which is connected with switches 49 and 50 which are grounded. Switch 49 closes when the engine temperature exceeds 'a certain amount and switch 50 closes when the engine oil level be comes too low.

Switch 49 is enclosed in a metal box 1| set into a pipe 12 which conducts engine cooling water and comprises a fixed grounded contact I3 and a contact 14 attached to a bimetal blade 15. As water temperature increases, blade 15 bends down and causes contact 14 to engage contact 13 when water temperature, which is a function of engine temperature, becomes excessive.

Switch 50 comprises a fixed grounded contact 80 and a movable contact 3| attached to a spring blade 82 engaged by a lever 83 pivoted at 84 and carrying a float B5 buoyed by oil in an oil sump 86 of the engine. When the level of oil in sump 86 becomes too low, switch 50 is closed.

Solenoid I surrounds a core 90 and a movable armature 9| connected by a rod 92 with a valve 93 normally opened by a spring 94 to connect a fuel tank 95 with a fuel injection 96 connected with the Diesel engine.

As shown in Fig. 2, the switch 3|, which parallels relay coil I2, is normally in off position. Switch 3| and coil I2 are in series with contacts 22, 2| and with circuits in parallel comprising solenoid I0, relay coil I3 and heater resistance 26 in series with normally closed contacts 42, 43.

Coincidentally with rendering operative the door operating mechanism of the bus by movement of a manually operable member, the switch 3| is moved to on position 3|, thereby connecting the battery 30 with one terminal of the buzzer magnet 48 through a circuit which includes: the wire 28, switch 3| at 3|, wire 39, flip disc 31, contacts 45 and 46 and heater resistance 41.

Normally when switch 3| is moved to on position 3|, heater resistance 41 and buzzer coil 48 do not receive current because switches 49 and 50 are open. Relay contact closing coil II recelves current from the battery 30 through the following circuit shown in Fig, 3: wire 28, switch 3|, Wire 33, contacts 45, 46, wire 21, coil II, and ground. Contact 2| engages contact 22. Coil I2 and solenoid I0 are in series with the battery through the following circuit: wire 28, coil I2, contacts 22, 2|, armature I1, frame I4 and solenoid I0. Solenoid I0 is not then sufficiently energized to close the fuel valve.

To shut off the engine in the normal manner, switch 3| is moved to off position and coil I2 is short circuited as shown in Fig. 2, and coil II is open circuited. Contacts 2|, 22 remain closed by virtue of coil I3 which is sufficiently energized for this purpose when coil I2 is short circuited. The battery 30 is then directly connected with the solenoid I0 and the heater 26, through switch 3|, contacts 22, 2|, armature I1 and relay frame I4. Solenoid I0, being energized, closes the fuel valve and the engine stops. After coil I2 is short circuited, heater 26 receives current suiiicient to cause such heating of blade 24 that it bends upwardly with force separation of contact 2| from contact 22 against the magnetic pull of coil I3. Therefore coil I3, solenoid I0 and heater 26 are open circuited. The status is then as shown in Fig. 2.

If, while switch 3| is in on position, either or both the switches 49, 50 are closed as shown in Fig. 4, the heater resistance 41 becomes effective to cause the disc 31 to bow downwardly to cause separation of contacts 45, 46 and contacts 42, 43 and engagement of contacts 44, 36 as shown in Fig. which short circuits coil I2. Solenoid I0 is then directly connected with the battery through the following circuit: wire 28, switch 3| at 3|, wire 39, contacts 44, 36, wire 34, contacts 22, 2|, armature I1, frame I4, solenoid I0. The solenoid is then. effective to close the fuel valve to stop the engine regardless of failure of the operator to do so although the buzzer 48 had sounded a warning before contacts 45, 46 had separated. Although the solenoid I0 has closed the fuel valve, it is still energized because coil I3 is holding contacts 2| 22 closed although coil II is open circuited by separation of contacts and 46 and coil I2 is short circuited by engagement of contacts 44 and 36. The circuit of coil I3 is then by way of closed contacts 2|, 22, armature l1 and frame I4.

When contacts 45, 46 separate, the heater resistance 41 is disconnected and the flip disc 31 cools and finally snaps to normal position shown to reengage these contacts. The contact separation time is substantially greater than the contact closing time. During the longer contact separation time, the bus may coast to a stop, although the driver may not move the switch 3I to off position before the contacts 45, 46 reengage. Assuming that the operator moves switch 3| to the off position before the contacts 45 and 46 reengage, coil I2 is short circuited but coil I3 is still effective to maintain engagement of contacts 2|, 22. When the disc 31 bows upwardly on cooling to reengage contacts 42 and 43, the heater 26 receives current and causes the blade 24 to bend upwardly to disconnect coil I3, solenoid I0 and heater 26 from the battery.

If the operator leaves the switch 3| in on position until after contacts 45, 46 reengage, coils II and I2 will be effective again as shown in Fig. 6, and the fuel valve will open because solenoid I0 is not then sufliciently energized. But the engine does not start although the fuel valve is open, since the operation of an engine starter is required to start it. The buzzer will sound again to remind the operator to move the switch 3| to off position. Then, as switch 3| is moved away from contact 33, coil II is disconnected. When switch 3| engages contact 32, coil I2 is short circuited and coil I3 becomes sufficiently energized to hold contacts 2|, 22 in engagement against the normal action of the blade 24. Contacts 45, 46, having been reengaged, and coil I2, having been short circuited by movement of switch 3| to off position, the heater 26 receives current sufficient to cause the blade 24 to bend upwardly and separate contacts 2| and 22, thereby disconnecting the battery from coil I3, heater 26 and solenoid I0.

If, after closing the fuel valve by energization of the solenoid in response to closing of a switch 49 or 50, the vehicle could coast down grade and drive the engine, means are provided for causing th vehicle brakes to be applied when the solenoid is energized. A relay 60 has a frame 6| connected by a spring hinge 62 with an armature 63 carrying a spring blade 64 supporting a contact 65 engageable with a contact 66 connected with electrically controlled means for causing application of the vehicle brakes. The magnet coil 61 of the relay is connected by wire 68 with switches 49 and and by wire 69 with solenoid I0. When solenoid I0 is energized in response to closing of a switch 49 or 50, coil 61 receives current and relay closes its contacts so that current can flow from the battery 30 through wire 10 and contacts 65, 66 to solenoid coil I00 (Fig. 1) which surrounds a core IM and an armature I02 connected with a valve I03 normally positioned by a spring I04 to connect a compressed air tank I05 with a chamber I06 having a flexible wall I01 connected by a lever I08 pivoted at I09 and carrying a brake shoe IIO engageable with a brake drum III rotating with the vehicle axle. When valve I03 is in the position shown, the shoe H0 is retracted from the drum III. When coil I00 is energized in response to closing of relay contacts 65, 86, armature I02 moves up to cause valve I03 to block fiow of compressed air to the chamber I06 and to connect the latter with a vent H2; and spring H3 effects the application of the vehicle brakes.

From the foregoing description, it is apparent that the invention provides means including the thermal switch 35 and its heater which is rendered effective by positioning the manually operated switch 3| in on position and by the closing of the emergency switch 49 or 50 to cause, by short circuiting the coil 12 which had been operating to reduce voltage applied to solenoid 10, the solenoid to become sufficiently energized to cause closing of the fuel valve 93 and provide means including the bimetal blade 24 and the heater 26 which is rendered effective to disconnect the solenoid from the current source when the manually operated switch is moved to off position in which it short circuits the coil 12.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A system of control comprising a current source, a solenoid, a relay switch having a fixed contact and a movable contact, an armature for moving the movable contact into engagement with the fixed contact and normally biased for separation of the contacts and having three magnet coils, the first of which is effective when connected with source to attract the armature to close the contacts and the second and third of which, when effectively energized, are operative to hold the contacts closed after the first coil is open circuited, a bimetal member connected with the relay armature and effective, when heated, to open the relay contacts against magnetic pull exerted by the third relay coil, a resistance element for heating the bimetal member, a manually operated switch having off and on positions, a circuit established across the source terminals when the manual switch is in on position and including the first relay coil whereby the relay contacts close, a circuit established across the source terminals by closing of the relay contacts and comprising the second relay coil in series with the relay contacts and a circuit including, in parallel, the third relay coil, the solenoid and the heater resistance, the second relay coil absorbing voltage such that the three parts in parallel are insufiiciently energized, movement of the manual switch to off position open-circuiting the first relay coil, and a short circuit of the second relay coil established by movement of the manual switch to off position whereby the third relay coil is operative to hold the relay contacts in engagement, the solenoid is fully energized and the heater resistance receives current rendering it operative to heat the bimetal member so that it will force separation of the relay contacts and third relay coil, the solenoid and the heater resistance are open-circuited.

2. A system according to claim 1 in which there is a second bimetal member, a thermal switch which includes the second bimetal member and three pairs of contacts actuated thereby namely, a first pair which are normally closed, a second pair which are normally open and a third pair which are normally closed, a second resistance for heating the'second bimetal member, in which the first pair of contacts is in the circuit of the-first relay coil and also in a series circuit paralleling. the first relay coil and comprising the second heater resistance of the thermal switch, a signal, and an emergency switch, in which the second pair of contacts of the thermal switch provides when closed a short circuit of the second relay coil, in which the third pair of contacts of the thermal switch is in series with the first mentioned heater resistance whereby, when the manual switch is in on position and an emergency switch is closed, the first pair of thermal switch contacts open in response to current flowin the second heater resistance to open circuit the first relay coil and the second heater resistancethe second pair of thermal switch contacts closes to short circuit the second relay coil and the third pair of thermal switch contactsopen to open-circuit the first heater resistance in consequence of which the third relay coil and the solenoid become effective and the relay contacts remain closed so long as the manual switch remains in on position, and whereby said relay contacts open provided the manual switch is moved to off position and the second bimetal member has cooled and returned to normal position to close the circuit of the first heater resistance.

3. An electrical system of control for a vehicle comprising an engine fuel control valve spring biased to open position, a solenoid for ClOSlIlg the valve, a normally open emergency switch which closes in case of abnormal engine operating conditions, a two-way manually operated switch having on and 01f positions, a current source, a relay having contacts, a first or contact closing coil and second and third coils for holding the contacts in engagement, the second and third coils bein in series with the current source and with the relay contacts, and the third coil being in parallel with the solenoid, a short-circuit of the second coil established by the manually oprated switch when in off position, a circuit between the current source and first coil established by the manually operated switch in .on position, means rendered effective by positioning the manually operated switch in on position and by the closing of the emergency switch for open-circuiting the first relay coil and for shortcircuiting the second relay coil, thereby rendering the solenoid effective to close the fuel valve, said relay contacts remaining closed by energization of the third relay coil, and means operating after moving the manually operated switch to "01? position for causing separation of the relay contacts, thereby open-circuiting the third relay coil and the solenoid.

4. An electrical system according to claim 3 and including a second relay having normally open contacts and a contact closing coil which is connected with the current source by the contacts of the first relay and by the closin of the emergency switch and means energized by the closing of the second relay contacts for causing the application of vehicle brakes.

5. An electrical system of control for a vehicle comprising an engine fuel control valve spring biased to open position, a solenoid for closing the valve, a normally open emergency switch which closes in case of abnormal engine operating conditions, a two-way manually operated switch having on and off positions, a current source, a voltage dropping element connectible in series with the current source and solenoid, and when so connected causing the solenoid to be insufficiently energized to close the fuel valve,

means rendered effective by positioning the manually operated switch in on position for establishing said series connection, means rendered effective by closing of the emergency switch while the manually operated switch is in on position to short-circuit the element whereby the solenoid becomes energized sufliciently to close the fuel valve, another short-circuit of the element established by the manually operable switch when in off position, and means rendered operative in response to the last mentioned short-circuiting of the element for causing the solenoid to be open-circuited.

6. An electrical system according to claim 5 having means which becomes effective to cause application of the vehicle brakes when the element is short-circuited while the manually operable switch is in on position and when the emergency switch is closed.

WILLIAM J. RADY. LYMAN A. RICE.

REFERENCES CITED lhe following references are of record in the file of this patent:

UNITED STATES PATENTS 

